1. Field of the Invention
The present invention relates to a method and apparatus that processes image signals, and more particularly, to a method and apparatus that controls brightness of an image processing device to improve brightness characteristics of image signals in a highlight mode.
2. Description of the Related Art
Generally, a device that processes image signals, such as a display device, enhances the brightness of an image by processing an input image signal via a highlight circuit. An image signal passed through the highlight circuit is amplified by pre-amplifier and main amplifier circuits and applied to, e.g., a cathode ray tube that produces light beams corresponding to the image signals. The brightness of the image displayed on a screen of the display device is determined on the basis of amplitude of the image signals. However, since amplification of the image signals is limited to a certain extent due to characteristics of circuit elements of the pre-amplifier and main amplifier circuits, it is occasionally impossible to display an image as brightly as a user wishes. Particularly, in a highlight mode enhancing the brightness of an image, image signals are likely to be saturated if the pre-amplifier and main amplifier circuits are not capable of sufficiently amplifying the image signals. If the image signals are saturated, the quality of the image is deteriorated.